New York - So, Victoria Azarenka, what went through your mind as your high-tension, high-quality U.S. Open quarterfinal victory over defending champion Sam Stosur stretched into a third-set tiebreaker?

"You don't want to know what I kept telling myself," Azarenka deadpanned Tuesday. "I would have to beep that, I think."

She went on to offer a cleaned-up version of what her thoughts had been - "Don't be a chicken" - while cobbling together a 6-1, 4-6, 7-6 (5) rain-interrupted win that eliminated Stosur, put the top-seeded Azarenka in her first semifinal at Flushing Meadows and assured her of retaining the No. 1 ranking no matter what happens the rest of this week.

"Definitely I don't want to stop. I really want it bad," Azarenka said about the prospect of adding a second Grand Slam trophy to the one she earned in January at the Australian Open. "I'm going to do absolutely everything I have, you know, to give it all here."

Because of rain that halted play on and off throughout the day, Azarenka was the only woman who got to enjoy a singles victory at the U.S. Open on Tuesday. The other women's quarterfinal on the schedule was suspended in progress because of rain, and four-time major champion Maria Sharapova will be trailing 2007 Wimbledon runner-up Marion Bartoli 4-0 when they resume today.

Sharapova got a bit of a reprieve from the weather during her previous match: She was down 2-0 in the third set against Nadia Petrova when a rain delay of 75 minutes came: After the break, Sharapova took five of the next six games. She'll get at least 15 hours to contemplate her deficit against Bartoli, who lost all eight sets they had played before Tuesday.

They were allowed to head to their hotels before 6 p.m., because the tournament wanted to free up Arthur Ashe Stadium for the night session and the main event: 2003 U.S. Open champion Andy Roddick's bid to postpone retirement yet again by beating 2009 champ Juan Martin del Potro in the fourth round.

That match was suspended because of rain and is scheduled to resume today. Play was halted right after Roddick went ahead 1-0 in a first-set tiebreaker Tuesday night. A little more than a half-hour later, the tournament called off play for the day.

Other matches stopped in progress, also in the first, included defending champion Novak Djokovic against No. 18 Stanislas Wawrinka, and No. 8 Janko Tipsarevic against No. 19 Philipp Kohlschreiber.

Getting through to the men's quarterfinals was No. 4 David Ferrer, who defeated No. 13 Richard Gasquet 7-5, 7-6 (2), 6-4.

That match, like most this week at Flushing Meadows, took second billing to one involving Roddick, who surprisingly announced last week that this tournament would be the last of his career. Since then, he picked up victories over players ranked 43rd and 59th, but the No. 7-seeded del Potro figured to provide more of a challenge. Del Potro is the only man other than Roger Federer, Rafael Nadal or Djokovic to win any of the last 30 Grand Slam titles.

The women's match pitted Stosur, the champion here last year, against Azarenka, who won the Australian Open to start the 2012 Grand Slam season.

Amazingly, as accomplished as Stosur is, she never had taken so much as a set off Azarenka in six previous tour meetings, including one match in qualifying.

That changed in Tuesday's second set, although forcing a third might not have given Stosur all that much self-belief. And in the end, Azarenka improved to 11-0 in three-setters this season, while Stosur fell to 9-7.

"I think I'm capable of beating her one day," the seventh-seeded Stosur said. "Just would have liked it to have been today."

Serving at 5-all in the third, Azarenka faced a break point and responded the best way possible, delivering a 92 mph ace, her only one of the match.

Asked about that at her news conference, Azarenka's response was telling: "When did I hit an ace? Did I hit one today, actually?"

Her serve is not exactly her strongest stroke, and Azarenka double-faulted five times, including while ahead 5-3 in the tiebreaker.

Azarenka used a swear word at her news conference to describe the second fault there, which landed several feet long. That was part of a topsy-turvy tiebreaker, in which Azarenka went ahead 4-0, and Stosur took five of the next six points to make it 5-5.

But that was when Azarenka buckled down.

"For sure, she really pushed me to dig deep," Azarenka said.

On the next point, a Stosur groundstroke clipped the net and went over, and Azarenka had the presence of mind, and soft hands, to respond with a drop-shot winner. That set up match point, which fittingly was a hit-'em-hard, 10-stroke exchange.

Eventually, Stosur sailed a backhand long as she dropped to a knee at the baseline.

At the opposite end, Azarenka dropped her racket, put her hands to her face, then looked skyward and said, "Oh, my God." She went to the middle of the court and raised her right index finger overhead - yes, she's No. 1 in the rankings, and she'll stay there for the time being - before blowing kisses to the crowd and throwing a ball into the stands.

She said later she was unaware that her victory locked up that top spot, and explained that a U.S. Open trophy come Saturday would mean a lot more.

Stosur would consider Azarenka a worthy successor.

"She never gives up. She fights very hard every single match she plays and she does it very well. That's probably part of the reason she's No. 1 at the moment," Stosur said. "She barely gives you any points. You have to work hard for every single point you get."